Internal brake



March 26, 1940.r

l o. RAsMussEN Erm. 2,195,261

\ INTERNAL BRAKE Filed sept. 2s, 193s 2 sheets-sheet 1 nvento s 07g( Was/zussen ad W. @ie/tee lttornegs March 26, 1.940. v 0, RAsMUssEN Er AL 2,195,261

INTERNAL BRAKE Filed sept. 28, 1958 :a sheets-sheet 2 :inventors @laf Wasmssez (Q Wm w Y, I Gttornegs .Patented Mar. 26, 1940 INTERNAL BRAKE Olaf Rasmussen and Earl R. Pierce, Dayton, Ohio;

assignors to General Motors Corporatiom Detroit,V Mich., a corporation of Delaware ApplicationSeptember 28, 1938, Serial No. 232,072

i l 12 Claims.

' 5 vide improvedmeans for adjusting the clearance of the brake shoes in that type of brakes making use of an articulating link anchorage.

Further objects include improved structural details by which the major object is accomplished, l the structure being simple,'effective and comparatively inexpensive.

On the drawings: Figure l shows in elevation 'and partly in section a iirst embodiment of the invention.

Figure 2 is a section on line 2 2 of Figure l. Figure 3 is a perspective of parts ,shown in Figure 2, the parts being in disassembled relation. Figure 4 -is a section on line 4--4 of Figure 2. Figure 5 is a section on line 5-5 of Figure 2. Figure 6 is a view in elevation of a second embodiment of the invention.

Figure 7 is a section on line 1-1 of Figure 6. Figure 8 is a section on line 8 8 of Figure 6.

Figure 9 is afview inelevation of a slightly recesses 23 to receive the thrust from articulating links 25 and 21 which links are pivoted to the shoes by means designated as a whole by numerals -29 and-3l. At 35 is shown a substantially conventional wheel cylinder which is to be asso- 40 ciated with the usual hydraulic brake system.

The wheel cylinder is equipped with pistons 31, sealing means 39 and plungers- 4I, the latter en gaging the shoes. -Numeral 33 represents the spring which is used to retract the shoes from contact with the drum.

in use, resulting in excessive clearance between the shoe andthe drum, mechanism is usually provided for reducing this c1earance. Adjusting mechanism of this kind is provided in the embodiment under discussion. 'Ihe adjustment is made at the connection. between the articulating links 25 and 21 and the shoes at the points 29 and 3l. In this form of the invention, link 25 is shown as made up of two parallel members 43 and 45.

Since the friction lining I9 becomesv worn down (Cl. 18S-79.5)

To the end of these members there is welded a thrust block v41 whichengages th'e anchor plate 2 I. It will be understood that the structure about to be described in connection with link 25 is duplicated in the case of link 21. One member 43 lies against one face of the web 49 of shoe I5. The other member 45 is slightly spaced from the opposite face of the web. A part 5I of a pin 53 rotates within an opening in web 49. Adjacent part 5I is an axial tooth part 55 and extending from part 55 is a spindle 51. Members 43 and 45 have registering openings 59 and 6I. The pin 53 has a head 63 which is eccentric to the part 5I and to the spindle. This head is rotatably mounted in the opening 6I. A ring 65 -of a diameter corresponding to the head and concentric therewith is received within opening 59. 'I'his ring 65 is provided with an eccentric open-l ing having teeth 61 to engage teeth 55 ofthe pin. Overlying ring 65 and spaced therefrom is a cupped disc 69 peripherally engaging member 43 and held in contact therewith by a spring 1I which surrounds the spindle 51 and engages a terminal abutment 13 carried by thespindle at -its end. The shoulder of pin` 53 between the h ead 63 and the bearing portion 5I has radial` serrations 15 to engage the serrations of a washer 11 located between the head and the web 49. 'I'his washer is held from rotation relative to the web by a tongue 19 displaced from the washer and projected into a hole 8I in the web. To effect a manual rotation of the pin 53, a slot is formed in head 63, the slot being intended to be l engaged by a suitable tool. If undue clearance develops between the drums and the shoe as a result ofv wear of the friction lining, the pin 53 may be manually rotated, its head 63 turning in the opening 6I and the ring 65 rotating within the opening 59. In so turning the pin the eccentric portion 5I may move in' a direction'to bring the shoe toward the drum and take up the excessive clearance. When so rotated the serrated parts separate and re-engage, the spring 1I yielding to permit the rotation. The spring 1I also serves to hold the-pinyin selectedA positions of adjustment. between part 43 and the web 49 of the shoe prevents rotation at this point when the shoe is released. When the brake is applied relative rotation between the web and theA link against thi:` frictional resistance is made possible, the rotation frequently being needed for the proper centering of the shoe relative to the drum.

Instead of employing the' eccentric adjustment between the linkage and the shoe it may be ar- 'I'he resiliently produced pressure 1 ranged between the linkage and the anchor plate. Such a location is. shown in Figures 6, and 8. In these figures the drum, the cover plate and the shoes'are marked |I, I3, I5 and I1 as before. At |0| is an anchor plate which, like cover plate I3, is rigidly fixed in position. To each shoe are pivoted the ends of a pair of links |03 and |05'by a pin |01. 'I'he links are spaced -to straddle the web of the shoe adjacent pivot |01 but are bent into contact at a point between their ends as shown at |09. The anchor plate |0Iv aided by the cover I3 journals two'spaced pins III. Each of these pins is formed with an eccentric portion ||3 to receive the recessed ends of the links |03 and |05. By means' of the eccentric I|3 and a washer II5 the position of the pin III is axiallyV determined. The head of the pin |I1 is shaped as at ||9 to receive a suitable `tool whereby the pin may be rotated. The end of the pin, remote from its head carries a concentric ratchet wheel I2I. Between the spaced pins there is an arched bridge plate |23 suitably secured as by welding to the anchor plate. Journaled in the anchor plate and in the arched plate is a pin|25 upon which are rotatably supported two pawls |21, one for engaging the teeth of each ratchet wheel. 'I'he pawls are spread apart by a spring |29. The opening within each pawl to receive the pivot pin |25 is elongated as shown by |3I, the extent of the elongation being a measure of the shoe clearance when the brakes are released.

In operation it will be understood that vthe shoes may be applied by a wheel4 cylinder as in the form of the invention shown by Figure 1, the I recessed ends of the articulating links rotate on the eccentric portions |I3 Voi the pins III. The axial pressure through the linkage tends to rotate the pin ||I owing to the eccentric point of application. Such rotation is resisted by the pawl and ratchet device. The spring |29 not only spreads the pawls so that they engage the teeth of the ratchets but it tends to hold the pawls in a position such that the clearance around the pins |25 is diametrically opposite its location as shown in Figure 6. Upon release of the brake applying means the extent of eccentricity -of the eccentric -I I3 and the length of the slot in the pawl determines the clearance between the drum and the shoe. If this clearance is excessive, adjustment may be necessary. To make the adjustment, pin II I is manually rotated, the eccentric thus pushing the shoe through the instrumentality of the linkage into contact with the drum. Simultaneously spring |29 lifts the pawl so that its clearance is diametrically opposite the position shown. At the moment of drum contact the pawl tooth will engage at some indeterminate point along a ratchet tooth. After such adjustment the pin III is manually rotated in a reverse direction to a limiting position determined by the positive engagement of the pawl and ratchet teeth and by the engagement of the pawl slot with its pivot as shown by Figure 6.

`In Figure 9 is shownv a slight modication. In this form of t'he invention the drum, the cover plate, shoes, anchor plate and linkage 'are identi# I e'd as in Figure 6. There is no change in the pin III with the exception that in place of ratchet wheel I2| there is a ratchet wheel- I2I provided with undercut teeth I3`I. A specially shaped pawl |33 is also used and amodied form of spring, a flat spring |35 anchored at |31, engages the twopawls.' The pawls rotateupon pivot pin |25 as before but they are not provided 'Il with the elongated opening shown in Figure 6.

the pawl an undercut extension. This undercutr extension performs4 the function of the elongation of the bearing opening in Lthe pawl which is shown and has been described in the case of Figure 6. j

We claim:

1. In a brake, a drum, shoes to frictionally engage the drum, means to elect such frictional engagement, a fixed anchorage, link means pivoted to said anchorageand to one of said shoes at a. point spaced from its end, and mechanism associated; with one of said pivoted connections to adjust the clearance between saidshoe and said drum without affecting the position ofthe other shoe.

2. The invention defined by claim 1, said mechanism including a pin rotatable within said link means and also rotatable about an eccentric axis with the connected member.

3. In a brake,a drum, shoes to frictionally engage the drum, means to effect such frictional pivoted to said anchorage and to one of said shoes at a point spaced at itsend, the connecting means betweensaid link means and said shoe comprising a pin having axially displaced eccentric parts rotatably mountedin the link and in the shoe, together with yielding means to maintain said shoe and link in positionsof eccentric adjustment.

5. In a brake, a drum, a shoe to frictionally engage the drum, means to effect such frictional engagement, a xed anchorage, link means between and pivotally connected to both said shoe and said anchorage, the pivotal connection between said shoe and link comprising a pin having a. head journaled in one of said parts, an eccentric portion journaled in the other part, a spindle co-axial with said eccentric part, a spring surrounding said spindle and a member actuated by the yielding pressure of s aid spring to frictionally resist relative rotation of said link and shoe.

6. In a brake, a drum, a shoe `to frictionally engage the drum, means to 'effect such frictional engagement, a xed anchorage, link means between and pivotally connected to both said shoe and said anchorage, said link means comprising two links straddling the web of said shoe, the pivotal connection between theshoe and the link .means comprising a pin having' a` head'journaled in one of said links, an axially spaced eccentric journaled in said shoe, adetachable member concentric with said head, journaled in the other link and non-rotatably mounted'on -sai'd pin,

lsaid pin formed with a spindle, a plate mounted on said-spindle and a springsurrounding the said spindle and pressing ysaid plate into fric.

tional contact vwith the second link.

'1. In a brake, adrum, a shoe to frictionally engage the drum, means to effect such -frictional gagement, a fixed anchorage, link means between engagement, ay xed anchorage, link means between and pivotally connected to both said shoe and said anchorage, said link means comprising two links straddling the web of said shoe, the pivotal connection between the shoe and the link means comprising a pin having a head journaled in one of said links, an axially spaced eccentric journaled in said shoe, a detachable member concentric with said head, journaled in the other link and non-rotatably mounted on said pin, said pin formed with a spindle, a plate mounted on said spindle and a spring surrounding the said spindle and pressing said plate into contact with the second link.

8. In a brake, a drum, first and second shoes to frictionally engage the drum, means to effect frictional engagement, a xed anchorage, ``link means pivoted to said anchorage and to said first shoe at a point spaced from its end, the connecting means between said link cmeans and said anchorage comprising a pin` having axially displaced eccentric parts rotatably mounted in said link means and said anchorage, said rotation being without eiect on said second shoe.

9. In a brake, a drum, rst and second shoes to frictionally engage the drum, means to" effect frictional engagement, a fixed anchorage, link means pivoted to-said anchorage and to said rst shoe at a point spaced from its end, ,the connecting means between said link means and said .anchorage comprising a pin having axially displaced eccentric parts rotatably mounted in said link means and said anchorage, together with a shoe.

10. In a brake, a drum, a shoe to frictionally engage the-drum, means to eect frictional enand pivotally connected to both said shoe and said anchorage, the connecting means between said link means and said anchorage comprising a pin having axially displaced eccentric parts rotatably mounted in said link means and lsaid anchorage, together with a ratchet wheel on said pin and a pivoted pawlon said anchorage to y to frictionally engage the drum., means to e'ect frictional engagement, a fixed anchorage, first and second links, said links being pivoted at spaced points to said anchorage and to saidA shoes at points spaced from their'ends, the connecting means between each link and said anchorage comprising a 'pin having axially displaced eccentric parts rotatably mounted in said linkand said anchorage, cooperating pawl and ratchet meansl on said anchorage and pin, said ratchet means having undercut teeth to provide a predetermined clearance between the shoe and the drum.

12. In a brake, a drum, two opposed shoes, means to spread said shoes, a xed anchorage, link means between each shoe and said anchorage and pivoted to both, the 'pivotal connections with the anchorage employing pins having eccentric portions for rotation in openings in the anchorage and in the links, pawls carried by said anchorage between said pins, each pin having a ratchet, and yielding means to spread said pawls with said ratchets.

OLAFRASMUSSEN. EARL R. PIERCE.

into locking engagement 

